In the process of the pilot produce, it is necessary to solve a series of problems from the trial to the scale-up process. The general synthesis process of the pilot produce needs to consider the characteristics of the reaction. For example, during the small-scale trial reaction, some materials are corroded by strong acid (concentrated sulfuric acid, etc.), which can be dripped through a constant pressure drop funnel.
In the pilot test produce, it is need to consider the use of enamel or glass drip tank. In addition, during the trial, when dropping of materials, it is need to consider the heat release of the reactive intermediate chemistry system after dropping the materials. In the small-scale trial reaction, the heat release is often not obvious. With good stirring during the trial, the specific heat release is often not observed. When at the pilot produce, many reactors have requirements for the stirring speed, and the stirring effect is not as ideal as the trial, so in the pilot produce, such problems need to be solved. According to the characteristics of the reaction system, the pilot reactor is selected. For example, in the general production process, the reactor facing strong acid can be made with an enamel kettle, but it is need to pay attention to the material to the flange interface during the dripping of corrosive materials.
Process stability often determines the benefits of a process. For small-scale and stable processes, after scale-up to pilot-scale, some processes are often easy to get high-purity samples during small-scale trials, but it is often difficult to get pure intermediate chemical products after scale-up. At this time, the optimization of the purification method should be considered. For example, some impurities can be removed by extraction, recrystallization, beating, washing, first adsorption on activated carbon or silica gel and then recrystallization or beating. The most undesirable method is column chromatography. The amount of solvent used is relatively large and the cost is too high.
During the trial, the amount of waste water is relatively small, and it can be collected directly in a small bucket for recycling. When starting the pilot produce, it is necessary to pay attention to the problem of recycling and applying waste liquid. For example, in a system involving a multi-step extraction reaction, after the solvent of the reaction system is concentrated, if it can be recycled for the next extraction, the recycling should be considered. The competition for exhaust gas is often carried out in a fume hood during a trial. There is no big problem with a slight leak of the exhaust gas. However, in the process of pilot produce or commercial produce, carelessness will cause a large amount of exhaust gas to overflow, corrode equipment, and be dangerous to people. Therefore, during the pilot produce, the absorption of exhaust gas should be fully estimated.